Preparation of peroxides



Patented Aug. 13, 1940 UNITED STATES PATENT OFFICE PREPARATION OF PEROXIDES tion of Germany No Drawing. Application July 6, 1938, Serial 4 Claims.

The alkali metal peroxides, particularly sodium peroxide, are now prepared by oxidation of an alkali metal such as sodium to the alkali metal monoxide, this monoxide being still further oxi- 5 dized to the alkali metal peroxide. A process for carrying out the manufacture of alkali metal peroxides in this way is described in the Carveth patent, No. 1,796,241.

It is now usual to utilize for supporting the charge in the oxidation process an iron rotary tube furnace. The use of iron equipment while satisfactory from the viewpoint of resistance to the relatively high temperatures utilized is objectionable in that it tends to render the resulting product impure by increasing the quantity of iron salts present therein.

We have now found that the alkali metal peroxides, particularly sodium peroxide, can be suitably prepared by oxidation of the alkali metal to the alkali metal monoxide, followed by further oxidation of the monoxide to the alkali metal peroxide, in rotary furnaces which are either formed of nickel or have their surfaces coming in contact with the charge coated with metallic nickel. We have found that rotary tube furnaces of nickel, or furnaces wherein the surfaces coming into contact with the alkali metal or alkali metal compounds are nickel-clad or plated with nickel, are especially suitable for the preparation of alkali metal peroxides in accordance with this process. In carrying out the oxidation of an alkali metal to the corresponding alkali metal peroxide in nickel rotary furnaces, or in furnaces having contacting surfaces formed of nickel or nickel alloys, the temperature is not raised to any substantial extent over 400 C. and is preferably held within the range 300 to 400 C.

We have found that alkali metal peroxides, more especially sodium peroxide, when manufactured in rotary tube furnaces of this type are considerably less unstable that those alkali metal peroxides produced in accordance with known processes in iron rotary tube furnaces. We have further found that aqueous solutions of alkali metal peroxides manufactured in this way are considerably more satisfactory when utilized for bleaching purposes, for example in the bleaching of textiles such as cotton goods, than the alkali metal peroxides now manufactured in iron equipment. The surprising stability of alkali metal peroxides prepared in accordance with our process is somewhat astonishing since it is gen- In Germany July 8, 1937 erally appreciated that nickel is a more active catalyst than iron for bringing about decomposition of compounds capable of yielding active oxygen.

In addition to nickel, we have found that suitable alloys of nickel may be utilized especially those alloys rich in nickel such as that sold commercially as Monel metal. It is sufficient that the surfaces coming in contact with the charge be of nickel or nickel alloys, and not necessary that the whole reaction vessel be formed of this metal. It may be clad or plated with nickel when it comes into contact with the product or charge.

It is to be understood that our invention is not to be restricted to specific details or methods of operation except as necessitated by the scope of the appended claims.

We claim:

1. A method for the preparation of an alkali metal peroxide which comprises oxidizing an alkali metal to alkali metal monoxide and then further oxidizing said alkali metal monoxide to alkali metal peroxide in a rotary tube furnace having the surfaces which come into contact with said product formed of a material selected from the group which COIlSiSLS of nickel and nickel alloys of high nickel content.

2. A method for the preparation of an alkali metal peroxide which comprises oxidizing an alkali metal to alkali metal monoxide and then further oxidizing said monoxide to alkali metal peroxide in a rotary tube furnace having its surfaces which come into contact with the reaction product formed of a metal selected from the group which consists of nickel and nickel alloys of high nickel content, the process being carried out at a temperature not exceeding 400 C.

'3. A method for the preparation of sodium peroxide which comprises oxidizing metallic sodium to sodium monoxide and then further oxidizing said sodium monoxide to sodium peroxide in a rotary tube furnace of which those surfaces coming into contact with said reaction product or charge are formed of a metal selected from the group which consists of nickel and nickel alloys of high nickel content.

4. A process as carried out in claim 3 wherein the temperature maintained during said reaction does not exceed 400 C.

ALBRECHT KRELL. EWALD HERZOG. 

